Comments on 05-177r0 "write same"

James.C.Hatfield at seagate.com James.C.Hatfield at seagate.com
Wed May 4 12:46:58 PDT 2005


* From the T10 Reflector (t10 at t10.org), posted by:
* James.C.Hatfield at seagate.com
*
You are correct in stating that there is no documented standard
way to 'enable or disable' SCT LBA Segment Access, but there <is> a
documented way for the device to separately report that
     a) it supports (or not) SCT (in general)     <and>
     b) is supports (or not) SCT LBA Segment Access

It is vendor unique whether or not there is a way to change the settings
of these bits.

Please refer to the SCT Technical report (1701DT rev 5, page 5)
      IDENTIFY DEVICE, word 206
      bit 0 = SCT Feature set supported (includes SCT status)
      bit 2 = LBA Segment Access (AC2) supported

I request that the SAT document needs to address what to do if bit 0 is set
to one
and bit 2 is cleared to zero.

Thank You !!!
-----------------------------------------------------------------
Jim Hatfield
Seagate Technology LLC
   e-mail:  James.C.Hatfield at seagate.com
   s-mail:  389 Disc Drive;  Longmont, CO 80503 USA
   voice:  720-684-2120
   fax....:  720-684-2711

==============================================================================
(from Curtis Stevens' notes of the discussion at the SAT meeting May 3
2005)

1. OPCODE - Is there a preferred hierarchy of choices for implementation?
      If a device does not support SCT, is there a preference for the other
2
      choices?

      Committee Respose:
      a. Wording was changed to reference SCT LBA Segment Access.
      There is no enable or disable for this capability.

3. Please clarify the meaning of "device implements SCT".  See 1a above.

4. What if the ATA device (target) 'supports' SCT, but does not have it (or
the LBA Segment Access subcommand) enabled?

Committee Response:
      There is enable/disable for SMART, but there is no enable or disable
for SCT.

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